Fig 2: Small interfering RNA-mediated downregulation of CDK11 and CK2 in breast cancer cells decreases cell viability and inhibits clonal survival. (A) Breast cancer cells were transfected with 30 nM single small interfering RNA (siRNA) or 15 nM each of the two siRNAs combined as indicated. After 96 hours, cell viability was determined relative to the untreated cells. Means ± standard errors (SEs) are presented. *P <0.05. **P <0.01, ***P <0.001 relative to untreated. ^ P = 0.055, # P <0.05, ## P <0.01, ### P <0.001 relative to siCtrl. (B) Triple-negative breast cancer (TNBC) cells were transfected twice with 30 nM single siRNAs or 15 nM each of the two siRNAs combined as indicated and as described in Materials and methods. Seven days after the second transfection, cell colonies were stained and counted. Means ± SE are presented. $ P <0.0001 relative to siCtrl and untreated. (C) Representative crystal violet stained colonies on 35 mm plates 7 days after the second siRNA transfection as described in (B). Cell lines are indicated above the plate images and siRNA transfections are indicated to the left of the plate images. CDK, cyclin-dependent kinase; CK2, casein kinase 2; si, small interfering.

Fig 3: Expression of CDK11 and CK2 protein complex members in untransformed and malignant breast cells. (A) Immunoblot analysis of cultured breast cell lines, as indicated above the blots. Proteins detected are indicated on the right side of the blots. Actin signal was used as the loading control. (B) Indirect immunofluorescent detection of CDK11, CK2α, and CK2α′ (red color) in breast cell lines. Cell lines are indicated above each set of images and proteins detected are indicated on the left side of the images. Blue, 4′,6-diamidino-2-phenylindole-stained nuclei. Scale bar: 100 μm. (C) Immunohistochemical detection of CDK11 proteins in human normal and malignant breast tissue. Type of breast tissue indicated on the left side of the images. Magnification indicated above the images; dotted ellipse, portion of the 100× image that is shown at 400×. Scale bars: 400 μm for 100× and 100 μm for 400× images. (D) Human microarray tissues stained for CDK11 were scored by two independent observers. The average value was taken and the results plotted for normal (n = 16) versus triple-negative breast cancer (TNBC; n = 44) tissues. Box, first to third (Q1 to Q3) quartiles; diamond, mean; line inside box, median; whiskers, minimum and maximums of data range. CDK, cyclin-dependent kinase; CK2, casein kinase 2.

Fig 4: Expression of CDK11 protein complex members in untransformed and malignant melanocytes. Immunoblot analysis of cultured melanocyte cell lines, as indicated above the blots. Proteins detected are indicated on the right side of the blots. Arrows on the left side of blots indicate dominant protein isoform bands. Actin signal was used as the loading control. Quantitation of signal relative to actin is indicated below each protein band.

Fig 5: siRNA-mediated down-regulation of CDK11 in BRAF- and NRAS-mutant melanoma cells decreases cell viability. A375 (A) and WM1366 (B) cells were transfected with increasing concentrations of siRNA directed against CDK11. After 96 h, cell viability was determined relative to the siControl transfected cells. Means ± SE from three experiments are presented. * = p < 0.05.